The spiral structure of the milky way can be explained by long lived quasi-static density waves<em>, </em><em>according to the lin-shu hypothesis. </em>Curiously, the waves of higher density gas and stars (seen as spiral arms) appear to remain static as stars move around the galaxy. This explained by assuming that the gravitational disturbances cause by the 'clumping' material in the arms does not affect the gravitational field of the galaxy as whole and is therefore negligible.
source: Astrophysicist
Answer:
Approximately
(assuming that the projectile was launched at angle of
above the horizon.)
Explanation:
Initial vertical component of velocity:
.
The question assumed that there is no drag on this projectile. Additionally, the altitude of this projectile just before landing
is the same as the altitude
at which this projectile was launched:
.
Hence, the initial vertical velocity of this projectile would be the exact opposite of the vertical velocity of this projectile right before landing. Since the initial vertical velocity is
(upwards,) the vertical velocity right before landing would be
(downwards.) The change in vertical velocity is:
.
Since there is no drag on this projectile, the vertical acceleration of this projectile would be
. In other words,
.
Hence, the time it takes to achieve a (vertical) velocity change of
would be:
.
Hence, this projectile would be in the air for approximately
.
<span>I would say greater than because as you do deeper, the pressure strengthens. If you were in a 10 ft deep pool and you dive all the way to the bottom, the ears usually pop. That's because of the pressure. Whereas if you were to go five feet, your ears wouldn't. It depends on the age of the person.
Hope this helps.</span>
When an ion is formed, the number of protons does not change. ... By removing an electron from this atom we get a positively charged Na+ ionthat has a net charge of +1. Atoms that gain extra electrons become negatively charged. A neutral chlorine atom, for example, contains 17 protons and 17 electrons.